Research has been conducted to provide various services at or above 100 Mbps to users and the services are under deployment as a 4th Generation (4G) communication system. Particularly, support of high-speed services with mobility and Quality of Service (QoS) ensured is an active study area in a Broadband Wireless Access (BWA) communication system such as Wireless Local Area Network (WLAN) and Wireless Metropolitan Area Network (WMAN) systems.
Transmission Control Protocol (TCP)/Internet Protocol (IP) is widely used for reliable connectivity between two end users irrespective of the type of communication system. TCP/IP means that an IP layer and its overlying TCP layer are used. Besides the TCP layer, many other layers may exist above the IP layer. For example, packets generated in various protocols such as User Datagram Protocol (UDP), Internet Control Message Protocol (ICMP), Internet Group Management Protocol (IGMP), and Real-Time Protocol (RTP) are encapsulated by the IP protocol, prior to transmission.
If no process at either endpoint of a TCP connection transmits data to its peer node, nothing is exchanged between both TCP modules. Unless this TCP connection is controlled, the TCP connection may be left as it is for hours, days, or months. Therefore, even though a relay router has failed or re-reruns or a link is damaged and then recovered, the TCP connection is maintained as long as at least one of the hosts (i.e., end users) at both endpoints of the TCP connection does not re-run. This TCP connection serves as a kind of garbage, consuming system resources. In this context, TCP KeepAlive is used to prevent resource waste caused by unnecessary maintenance of a TCP connection.
In TCP KeepAlive, a TCP KeepAlive probe packet is transmitted to a TCP peer node in a predetermined cycle. If a TCP ACKnowledgment (ACK) is not received in response to the TCP KeepAlive probe packet, a TCP connection session is closed, that is, released. In general, a timer for TCP KeepAlive may be set to any time from 15 minutes to 2 hours.
If one of TCP end users is a Mobile Station (MS) that accesses an IP network through a wireless communication system, the MS may access the IP network through a Base Station (BS) and an Access Service Network GateWay (ASN-GW). In the absence of traffic transmitted/received via a radio interface for a predetermined time, the MS may switch to an idle mode and turns off a wireless module, thereby minimizing power consumption. A timer for idle mode is generally set to a smaller value than the timer for TCP KeepAlive.
If the timer for TCP KeepAlive expires after the MS enters the idle mode, a remote end user generates a KeepAlive packet and transmits the KeepAlive packet to an ASN-GW being a core entity of a Core Network (CN) to which the MS is connected through the IP network, without knowledge of the state of the MS. A BS of a radio access network pages the MS in response to a notification of the ASN-GW so that the KeepAlive packet may be transmitted to the MS. The MS performs network reentry to the BS in response to the paging, receives the KeepAlive packet, and replies the remote end user with an ACK packet. Subsequently, when a predetermined time elapses without packet transmission, the MS returns to the idle mode.
The network reentry involves many procedures for MS re-authentication, Layer 1 (L1)/Layer 2 (L2) resource reallocation, and reconfiguration of a radio connection. Accordingly, network reentry and paging performed just for TCP KeepAlive result in unnecessary resource consumption of related entities and radio interfaces.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.